The invention relates to a tag device.
DE 196 28 504 A1 discloses a tag device with an integrated circuit capacitively coupled to an antenna, as well as a method of manufacturing such a device. The tag device comprises an integrated circuit, electrode plates in the integrated circuit, an insulating film covering the electrode plates, antenna terminals which face one of the electrode plates, with the insulating film in between, antennas which are connected to the relevant antenna terminals, and enveloping parts. The known tag device stores information, for example, relating to the type and price of a commercial article and transmits an information-based signal as a response to electromagnetic waves received from a sensing device.
A transponder which receives electromagnetic waves from a sensing device via antennas is known from EP 0 585 132 A1 quoted in DE 196 28 504 A1. The reception of electromagnetic waves causes a response circuit of the transponder to supply information as a response to the received waves and to transmit the information via the antennas to the sensing device. The current for the response circuit is supplied by means of the power of the received electromagnetic waves. When the transponder receives the electromagnetic waves from the sensing device with its antennas, a current supply circuit converts the power of the received waves into DC power and feeds it to the response circuit so that this circuit is switched on The response circuit demodulates a signal received from the sensing device, analyzes this signal and then supplies information stored in the response circuit. The output signal of the response circuit is applied to the antennas via a coupling capacitor. The sequence of information is transmitted via the antennas to the sensing device.
The response circuit and the current supply circuit as described in EP 0 585 132 A1 are formed on a semiconductor chip in the form of a generally flat integrated circuit. The integrated circuit is connected to the antennas by means of wires. Each antenna also has a generally flat form and extends in a plane outwards, comprising the flat integrated circuit. The overall integrated circuit including the antennas is positioned with its oppositely located main faces between two envelopes by which it is encapsulated. The envelopes are formed from a synthetic material and also have a flat shape. The resultant construction constitutes a tag device which can be provided on, for example, a commercial article so as to transmit information to a sensing device.
In the tag device known from EP 0 585 132 A1, the wires and antennas and the wires and the terminals of the integrated circuit are connected by means of wire contacts. These are liable to connection defects due to blows or shocks and require great precision in their manufacture.
In the tag device described in DE 196 28 504 A1, these wire contacts are replaced by an antenna in the tag device described in this specification, while a generally flat electrode plate is arranged on a main surface of the integrated circuit in the tag device and is connected to the response circuit of the tag device. A generally flat antenna terminal is connected to the antenna and faces the electrode plate by a predetermined distance. A capacitance by which the antennas are electrically coupled to the integrated circuit, is formed between the antenna terminal and the facing electrode plate.
It is an object of the invention to provide a simplified and low-cost tag device.
This object is solved by a tag device for receiving, processing and/or transmitting data signals by means of an integrated electronic data-processing circuit formed in an essentially plane substrate body and at least two electrodes arranged on the plane substrate body, which electrodes are connected to the data-processing circuit in such a way that they are adapted to transmit and/or receive the data signals and/or electric power supply energy by means of offset currents produced via a quasi-static, electric alternating field.
The invention further provides a system using a tag device for receiving, processing and/or transmitting data signals by means of an integrated electronic data-processing circuit formed on a substantially plane substrate body and at least two electrodes arranged on the plane substrate body of the tag device, as well as a reading apparatus comprising electrodes corresponding to the electrodes of the tag device, in which system, in operation, the tag device is brought into a spatial correlation with the reading apparatus in such a way that an exchange of electric power supply energy and/or the data signals takes place between the electrodes of the tag device and the corresponding electrodes of the reading apparatus by means of offset currents produced via a capacitive coupling with a quasi-static, electric alternating field.
The invention also provides a reading apparatus for a system of the above-mentioned type according to the invention.
The tag device according to the invention may be arranged completely on a one-piece substrate body without any additional external components. A semiconductor body may serve as such a substrate body on which or in which the data-processing circuit is formed simultaneously. Conventional semiconductor materials such as silicon or semiconducting compounds but also semiconducting synthetic materials may be used for the semiconductor body. The tag device according to the invention is in direct exchange of electric power supply energy and/or the data signals with corresponding electrodes of a reading apparatus adapted to the tag device via the electrodes which are directly arranged on the substrate body, which electrodes may also be formed by parts of the substrate itself. The coupling required for this exchange is effected capacitively, i.e. by a quasi-static electric field, at very close distances. By avoiding microwaves for the transmission, stray fields are minimized so that the transmission and sensing reliability is increased. In addition to the simplified structure of the tag device according to the invention and the associated reading apparatus, a universal possibility of use is also achieved for applications which are sensitive to security. The tag devices according to the invention may be used as machine-readable and rewritable product tags for storing product information and client service data. They may be further used in tags or stickers for biochemical sample containers, accumulator packets, data storage media and the like. Tag devices according to the invention may be used as security characteristics for, for example, passports, driving licenses or banknotes as a form of forgery protection or they may be used for machine-reading these documents. Due to their very compact structure and very small dimensions, the tag devices according to the invention may also be used as, for example, marks of genuineness for products and works of art. They may be further provided as hidden, secret tags on different parts of vehicles such as motorcars and bicycles on which they serve, for example, as marks of recognition for retrieving stolen goods. Tag devices according to the invention may also be used as inexpensive, electronic tickets with a high protection against forgery.
Due to their simple structure, the tag devices according to the invention can be manufactured at very low cost. The integrated data-processing circuit is preferably made in a standardized CMOS manufacturing process in which the devices, particularly electrodes and associated circuit arrangements are also comprised on the substrate body, without additional, external components. Particularly, no energy store for storing the power supply energy is required. Energy and data exchange is only realized by means of capacitive coupling In such a tag device, the substrate body may have a surface of approximately 1 qmm or less when manufactured on a silicon basis. Since neither connection contacts nor special housings are required for the tag device, the manufacturing costs are very low and are particularly only about {fraction (1/10)} of the manufacturing costs for microwave-coupled tag devices.
In the tag device according to the invention, at least two of the electrodes may optionally be arranged on that surface of the substrate body on which the data-processing circuit is formed, or at least one of the electrodes may be arranged on this surface and at least a further one may be arranged on a facing surface of the substrate body. Preferably, the material of the substrate body itself serves as this further electrode on the substrate body surface facing the data-processing circuit. Simple adaptations to the desired fields of application are possible by virtue of these variants.
In addition to the direct capacitive coupling between the electrodes of the tag device according to the invention and the electrodes of the reading apparatus, indirect capacitive coupling via at least one auxiliary electrode is also possible in a simple way in the tag devices according to the invention. To this end, a further embodiment of a tag device according to the invention additionally comprises a supporting body comprising at least one auxiliary electrode which is at least essentially plane. The substrate body with the electrodes and the data-processing circuit is arranged on this supporting body in a position in which a capacitive coupling of each auxiliary electrode with at least substantially exclusively one of the electrodes on the substrate body is realized. Without giving up the principle of capacitive coupling in this case, a sufficiently intensive electrostatic coupling may also be achieved with such an arrangement when, for reasons of maintenance, the electrodes of the reading apparatus and the tag device cannot be put close enough together to achieve a sufficient capacitive coupling directly between the reading apparatus and the electrodes on the substrate body. The auxiliary electrodes are put very close to the electrodes on the substrate body in such an arrangement so that a sufficiently high capacitance is obtained in this case. A corresponding, sufficient capacitance should then be established between the electrodes of the reading apparatus and the auxiliary electrodes, for which a plane extension of the auxiliary electrodes dimensioned in accordance with the space to be maintained should be selected. The capacitance between each electrode on the substrate body and the auxiliary electrode, on the one hand, as well as the capacitance between the auxiliary electrode and the electrode of the reading apparatus, on the other hand, are then arranged in series during operation and establish a capacitive coupling between the substrate body and the reading apparatus. To this end, each auxiliary electrode covers the substrate body at least substantially at the area of the electrode on the substrate body, which electrode capacitively couples with said auxiliary electrode.
In a further embodiment of the invention, in which at least one of the electrodes of the tag device is arranged on the surface facing the data-processing circuit on the substrate body, the substrate body with the electrodes arranged thereon and the data-processing circuit is arranged between auxiliary electrodes arranged in two planes. This provides the possibility of a simple coupling of the auxiliary electrodes with the electrodes on the substrate body thus configured.
In a system according to the invention, comprising a tag device of the type described and a reading apparatus, the reading apparatus and the tag device may be preferably formed with mutually complementary, form-locking recesses. These serve for a rapid joining of the reading apparatus and the tag device in the correct position. Such recesses prove to be advantageous because the high positioning accuracy, required for reasons of the small dimensions of the tag device according to the invention, is easily achieved for the coupling to be established between the reading apparatus and the tag device.
Further advantageous embodiments of the invention are defined in the dependent claims.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.